Sensor arrangement for engine control system

ABSTRACT

A number of embodiments of feedback control systems for two-cycle, internal combustion engine management systems. Each embodiment employs an exhaust system sensor which senses the exhaust gases by drawing exhaust gases from the exhaust of the engine. In some instances this is done directly from the cylinder and in others it is done in the exhaust system. In each embodiment, the sensor is provided in an accumulator chamber so as to provide an accurate signal of instantaneous engine running conditions. The use of the accumulator chamber insures that the combustible gases will not be diluted with fresh air charge, but will be able to purge from cycle to cycle so as to provide cycle-by-cycle information. Various arrangements are provided for protecting the sensor element including serpentine flow paths, shields, the direction in which the exhaust gases are delivered, lubricant catalysts, conduit shape, sensor cooling and combinations of these features. Furthermore, various structural elements help protect the exterior of the oxygen sensor from damage, such as housings, placement of the sensor within depressions in the engine and integrally forming the sensor in the cylinder block.

BACKGROUND OF THE INVENTION

This invention relates to an engine control system and more particularlyan improved sensor arrangement for such a system as particularly appliedto two-cycle crankcase compression internal combustion engines.

The advantages to two-cycle internal combustion engines because of theirsimplicity and relatively low cost are well noted. However, the portingarrangement for these engines gives rise to certain problems inconnection with exhaust emission control. Because of the overlap betweenthe scavenging action and the exhaust, there is some difficulty ininsuring good exhaust emission control. This is because some of thescavenging charge may actually pass out the exhaust port, and thuspresent the risk of unburned hydrocarbons escaping to the atmosphere.

In addition to this problem, because of the fact that the lubricant in atwo-cycle engine is normally not recirculated but is consumed in theengine during its running, there is a likelihood of lubricant in theexhaust gases. Thus, this type of engine presents particular problems incontrolling exhaust gas emissions.

Such features as the use of fuel injection and exhaust gas treatment aswell as feedback controls have been proposed so as to permit thecontinued use of two-cycle engines, even in spite of environmentalconcerns. However, the use of some of these exhaust control methods alsoare made difficult by the inherent nature of the two-cycle engineoperation.

For example, it has been the practice in four-cycle engines to usefeedback control systems to maintain the desired air/fuel ratio underall running conditions. These feedback control systems employ oxygensensors in the exhaust or other sensors to insure that the air/fuelratio is maintained within the desired range and also to control exhaustemissions. The most commonly used type of sensor senses the presence ofoxygen in the exhaust gases in order to provide an indication as towhether or not a stoichiometric mixture is being burned. However, due tothe scavenging effect and the likelihood of some air charge in theexhaust gases, oxygen sensors may not be completely practical in theseapplications. This is because the oxygen sensor may receive some oxygenrather than exhaust gases during the final portions of the exhaustscavenged phase. Devices have been proposed for attempting to overcomethese problems, but for a variety of reasons they have not beenparticularly successful.

It is, therefore, a principal object of this invention to provide animproved engine management system particularly adapted for use withtwo-cycle crankcase compression engines.

It is a further object of this invention to provide an improved sensorarrangement for feedback control in such engine management systems.

It is a still further object of this invention to provide an improvedexhaust sensor arrangement for a two-cycle crankcase compression enginewherein the sensor is mounted and operated in such a way as to insurethat primarily exhaust products will be delivered to the sensor.

In order to permit more accurate exhaust gas sensing in two-cycleengines, it has been proposed to provide an oxygen sensor arrangementwherein the oxygen sensor receives gases directly from the combustionchamber but only at times when the scavenging process is not at such astage where the scavenge gases may contact the oxygen sensor. However,the type of systems proposed for this purpose have, for the most part,required some form of valving arrangement for insuring that the oxygensensor only receives exhaust gases. This provides not only a complicatedstructure, but also a possible source for malfunction.

It is, therefore, a still further object of this invention to provide animproved oxygen sensor arrangement for two-cycle engines wherein it canbe insured that the sensor receives exhaust products from the engine butnot scavenging gas products.

As has been previously noted, the exhaust gases in two-cycle engines maycontain amounts of lubricant. The type of exhaust sensors utilized forengine management systems are relatively sensitive and can be easilycontaminated if lubricant comes in contact with them.

It is, therefore, a still further object of this invention to provide animproved exhaust sensor arrangement for an engine wherein the sensor,per se, is protected from contamination.

The type of exhaust sensors used for engine management systems are alsosensitive to vibrations and mechanical shock and can be disabled ifsubjected to an impact force. It is, therefore, a still further objectof this invention to provide an exhaust sensor arrangement for an enginewherein the sensor is protected from potentially damaging mechanicalshock.

SUMMARY OF THE INVENTION

A first feature of this invention is adapted to be embodied in a controlsystem for an internal combustion engine having a combustion chamberthat varies in volume cyclically during engine operation. An exhaustsystem receives exhaust gases from the combustion chamber during a cycleof engine operation. A fuel supply system is provided for supplying fuelto the engine for combustion in the combustion chamber. An accumulatorchamber is provided that affords a volume in which exhaust gases fromthe combustion chamber may be accumulated and which communicates withthe combustion chamber for at least a portion of the engine operatingcycle. A sensor is provided in the accumulator chamber for sensing theair/fuel ratio and providing a control signal for control of the fuelsupply system. The inner surfaces of the accumulator chamber may becoated with a catalyst for preventing oil and exhaust gases fromcontaminating the sensor. A filter may be provided to intercept oilcontained in the exhaust gases before reaching the sensor.

Another feature of the invention is adapted to be embodied in a controlsystem for a ported engine having at least two combustion chambers, eachof which cyclically vary in volume during a single cycle of operation.An accumulator chamber containing an exhaust sensor for sensing thecondition of the exhaust gases is provided. This exhaust sensor providesa signal for controlling a fuel supply system that supplies fuel to thecombustion chamber for combustion therein.

A still further feature of the invention is adapted to be embodied in acontrol system for a two-cycle internal combustion engine having acombustion chamber that varies cyclically during engine operation. Anexhaust system receives exhaust gases from the combustion chamber duringa cycle of engine operation. A fuel supply system supplies fuel to theengine for combustion in the combustion chamber. An accumulator chamberprovides a volume in which exhaust gases from the combustion chamber mayaccumulate and communicates with the combustion chamber for at least aportion of the engine operating cycle. A sensor is provided in theaccumulator chamber for providing a control signal for control of thefuel supply system. A protective sleeve around the sensor prevents oilin the exhaust gases from contaminating the sensor. The sensor may bemounted in recessed relation to the engine, or may be protected by acover, to help minimize damaging external impacts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial schematic view showing an outboard boat motorconstructed in accordance with an embodiment of the invention in sideelevation, in rear plan with a portion of the protective cowling removedand in a schematic cross-sectional view, taken through one cylinder ofthe engine with the fuel supply system and feedback control system beingshown in part schematically;

FIG. 2 is an enlarged side elevational view of the engine in the powerhead portion and looking in the same direction as the lower right-handside view of FIG. 1;

FIG. 3 is a top plan view of the engine depicted in FIG. 2;

FIG. 4 is a cross-sectional view taken in the same direction as the rearelevational view of FIG. 1 on an enlarged scale and with portions of theengine broken away to more clearly show the construction;

FIG. 5 is a cross-sectional view of the portion of the outboard motor ofFIG. 4 below the power head forming a continuation of FIG. 4 with afurther part broken away and shown in section;

FIG. 6 is an enlarged cross-sectional view looking in the same directionas FIG. 2 with portions broken away and showing the sensor arrangementfor the feedback control system of this embodiment;

FIG. 7 is a further enlarged cross-sectional view, taken in the samedirection as FIG. 6, but shows the sensor element, per se, and itsprotective arrangement;

FIG. 8 is a partial schematic view and shows the relation of the sensorto one of the two cylinders with which it is connected in thisembodiment;

FIG. 9 is a view, in part similar to FIG. 8, and shows the connection ofthe sensor to the other cylinder in this embodiment;

FIG. 10 is a graph showing the cycle of operation of each of the threecylinders of the engine of this embodiment in relation to crank angle,the condition of the porting communications to the sensor in the sensedcylinder and the controlling cylinder, the pressure in the accumulatorchamber where the sensor element is positioned, and the sensor timinginterval;

FIG. 11 is a view, in part similar to FIG. 4, with other portions beingshown schematically, and illustrates another embodiment of theinvention;

FIG. 12 is a side elevational view, in part similar to FIG. 2, and showsa further embodiment of the invention;

FIG. 13 is a rear elevational view, with a portion broken away, of theembodiment of FIG. 12;

FIG. 14 is an enlarged side elevational view, in part similar to FIGS. 2and 12, and shows another embodiment of the invention;

FIG. 15 is a top plan view of the embodiment of FIG. 14;

FIG. 16 is a rear elevational view of this embodiment, with a portionbroken away, and is similar in part to FIGS. 4, 11 and 13;

FIG. 17 is a side elevational view, in part similar to FIGS. 2, 12 and14, and shows yet another embodiment of the invention;

FIG. 18 is a top plan view of this embodiment;

FIG. 19 is a rear elevational view of this embodiment, with a portionbroken away and shown in section, and is in part similar to FIGS. 4, 11,13 and 16;

FIG. 20 is an enlarged partially cross-sectional view, taken through thesensor of this embodiment;

FIG. 21 is a side elevational view, in part similar to FIGS. 2, 12, 14and 17 of a still further embodiment of the invention;

FIG. 22 is a rear elevational view of this embodiment, with a portionbroken away and shown in cross-section, and is in part similar to FIGS.4, 11, 13, 16 and 19;

FIG. 23 is a cross-sectional view, taken in the area between the powerhead and drive shaft housing of an outboard motor constructed inaccordance with a yet further embodiment of the invention;

FIG. 24 is a cross-sectional view, in part similar to FIG. 23, and showsyet another embodiment of the invention;

FIG. 25 is an enlarged cross-sectional view, in part similar to FIGS. 4,11, 13, 16, 19 and 22 of still another embodiment of the invention;

FIG. 26 is a side elevational view, in part similar to FIGS. 2, 12, 14,17 and 21 of a still further embodiment of the invention;

FIG. 27 is a rear elevational view, with a portion broken away, in partsimilar to FIGS. 4, 11, 13, 16, 19, 22 and 25 for this embodiment;

FIG. 28 is a top plan view of this embodiment;

FIG. 29 is an enlarged cross-sectional view of the sensor arrangementfor this embodiment;

FIG. 30 is a graph, in part similar to FIG. 10, showing the operation ofthis embodiment;

FIG. 31 is an enlarged cross-sectional view, taken through a sensorarrangement constructed in accordance with yet another embodiment of theinvention;

FIG. 32 is a view, with a portion broken away and shown in section, of asensor arrangement constructed in accordance with still anotherembodiment of the invention, and is in part similar to FIGS. 6, 20, 29and 31;

FIG. 33 is a side elevational view, in part similar to FIGS. 2, 12, 14,17, 21 and 26, of still a further embodiment of the invention;

FIG. 34 is a rear elevational view, with portions broken away, in partsimilar to FIGS. 4, 11, 13, 16, 19, 22, 25 and 27 of this embodiment;

FIG. 35 is a top plan view of this embodiment;

FIG. 36 is an enlarged cross-sectional view, taken through the sensorarrangement of this embodiment;

FIG. 37 is a view looking from the direction perpendicular to that ofFIG. 36, and shows how the sensor element is mounted in this embodiment;

FIG. 38 is a cross-sectional view, in part similar to FIG. 36, and showsa further embodiment of a sensor arrangement;

FIG. 39 is a cross-sectional view, in part similar to FIGS. 36 and 37,showing a still further sensor arrangement embodiment;

FIG. 40 is a cross-sectional view, in part similar to FIGS. 36, 38 and39, of a still further sensor arrangement embodiment;

FIG. 41 is a cross-sectional view, in part similar to FIGS. 36, 38, 39and 40, of a still further embodiment of a sensor arrangement, inaccordance with the invention;

FIG. 42 is a cross-sectional view of another embodiment of a sensorarrangement in accordance with the invention;

FIG. 43 is a cross-sectional view of a still further sensor arrangementembodiment;

FIG. 44 is a cross-sectional view of another sensor arrangementembodiment;

FIG. 45 is a partial schematic view showing the relation of the oxygensensor to two cylinders with which it is connected, similar to FIGS. 8and 9 combined;

FIG. 46 is a graph illustrating the pressure peaks within the twocylinders to which the sensors shown in FIG. 45 are connected;

FIG. 47 is an enlarged side elevational view of an engine showing anoxygen sensor of the present invention mounted within a protectivecover;

FIG. 48 is an enlarged rear elevational view of the sensor andprotective cover of FIG. 47;

FIG. 49 is an enlarged top plan view of the sensor and protective coverof FIG. 47;

FIG. 50a is a partial vertical cross section through an engine similarto the view of FIG. 4, illustrating yet another sensor mountingarrangement in accordance with the invention;

FIG. 50b is a top plan view of the engine depicted in FIG. 50a;

FIG. 51 is a side elevational view of an engine showing an oxygen sensorconnected to cylinders 1 and 3 and with exhaust communication passagesformed integrally with the cylinder block of the engine;

FIG. 52 is an enlarged cross-sectional view of the oxygen sensor of FIG.51 showing exhaust communication passages formed integrally with thecylinder block;

FIG. 53 is an enlarged partial sectional view similar to FIG. 6 showinga modified oxygen sensor element sleeve;

FIG. 54 is an enlarged cross-sectional view of another oxygen sensorarrangement similar to that shown in FIG. 36;

FIG. 55 is a perpendicular view to that of FIG. 54 similar to that ofFIG. 37 and illustrates how the sensor element is mounted in thisembodiment;

FIG. 56 is an enlarged cross-sectional view of a further embodiment ofan oxygen sensor arrangement in accordance with the invention having afilter positioned in the inlet conduit;

FIG. 57 is an enlarged cross-sectional view of a further embodiment ofan oxygen sensor arrangement, similar to that shown in FIG. 36, with afilter positioned within an inlet conduit and having an accumulatorchamber coated with a catalyst;

FIG. 58 is a view taken perpendicularly to that of FIG. 57, illustratinghow the sensor element is mounted in this embodiment;

FIG. 59 is a side elevational view of an engine, similar to that shownin FIG. 2, showing yet another oxygen sensor arrangement in accordancewith the invention;

FIG. 60 is a rear cross-sectional view of the engine of FIG. 59;

FIG. 61 is an enlarged cross-sectional view of the oxygen sensorarrangement of FIGS. 59 and 60;

FIG. 62 is a partial sectional view of a cylinder head of an engineillustrating an alternative mounting arrangement for an oxygen sensor inaccordance with the present invention incorporating a cooling water flowtherearound;

FIG. 63 is a flow diagram illustrating a typical gas flow into an inletport of a cylinder leading to an oxygen sensor;

FIG. 64 is an enlarged, cross-sectional view showing an improved inletport in a cylinder of an engine leading to an oxygen sensor arranged inaccordance with the present invention;

FIG. 65 is an enlarged cross-sectional view of the inlet port of FIG.64;

FIG. 66 is an alternative embodiment of the inlet port of FIG. 65;

FIG. 67 is an enlarged, cross-sectional view of an angled inlet port ina cylinder of an engine leading to an oxygen sensor arranged inaccordance with the invention;

FIG. 68 is a cross-sectional view of a still further embodiment of aninlet port leading to an oxygen sensor arranged in accordance with theinvention; and

FIGS. 69a and 69b are two views of a cylinder of an engine showing aninlet port for an oxygen sensor opening into a combustion chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now in detail to the drawings, and to the embodiment of FIGS.1-10 initially by reference to FIG. 1, an outboard motor is shown in thelower portion of this figure in rear and side elevation and is indicatedgenerally by the reference numeral 21. The invention is shown inconjunction with an outboard motor because the invention has particularutility in conjunction with two-cycle crankcase compression engines.Such engines are normally used as the propulsion device for outboardmotors. For these reasons, the full details of the outboard motor 21will not be described and have not been illustrated. Those skilled inthe art can readily understand how the invention can be utilized withany known type of outboard motor.

The outboard motor 21 includes a power head that is comprised of apowering internal combustion engine, indicated generally by thereference numeral 22. The engine 22 is shown in the lower left-handportion of FIG. 3 and in the lower view of FIG. 1, with a portion brokenaway, and in a schematic cross-sectional view through a single cylinderin the upper view of this figure. The construction of the engine 22 willbe described later, but it should be noted that the engine 22 is mountedin the power head so that its crankshaft, indicated by the referencenumeral 23, rotates about a vertically extending axis. The engine 22 ismounted on a guide plate 24 provided at the lower end of the power headand the upper end of a drive shaft housing, to be described. Finally,the power head is completed by a protective cowling comprised of a lowertray portion 25 and a detachable upper main cowling portion 26.

The engine crankshaft 23 is coupled to a drive shaft (not shown) thatdepends into and is rotatably journaled within the aforenoted driveshaft housing which is indicated by the reference numeral 27. This driveshaft then continues on to drive a forward/neutral/reverse transmission,which is not shown but which is contained within a lower unit 28. Thistransmission provides final drive to a propeller 29 in any known mannerfor propelling an associated watercraft.

A steering shaft (not shown) is affixed to the drive shaft housing 27.This steering shaft is journaled for steering movement within a swivelbracket 31 for steering of the outboard motor 21 and the associatedwatercraft shown in phantom and indicated generally by the referencenumeral 30 in a well-known manner.

The swivel bracket 31 is, in turn, pivotally connected by a pivot pin 32to a clamping bracket 33. The clamping bracket 33 is adapted to bedetachably affixed to the transom of the associated watercraft 30. Thepivotal movement about the pivot pin 32 accommodates trim and tilt-upoperation of the outboard motor 21, as is well known in this art.

Continuing to refer to FIG. 1 and now primarily to the lower left-handside view and the upper view, the engine 22 is depicted as being of thetwo-cycle crankcase compression type and, in the specific illustratedembodiment, is of a three-cylinder in-line configuration. Although thisparticular cylinder configuration is illustrated, it will be apparent tothose skilled in the art how the invention may be employed with engineshaving other numbers of cylinders and other cylinder orientations. Infact, certain facets of the invention may also be employed with rotaryor other ported type engines.

The engine 22 includes a cylinder block 34 in which three cylinder bores35 are formed. Pistons 36 reciprocate in these cylinder bores 35 and areconnected by means of connecting rods 37 to the crankshaft 23. Thecrankshaft 23 is, in turn, journaled for rotation within a crankcasechamber 38 in a suitable manner. The crankcase chamber 38 is formed bythe cylinder block 34 and a crankcase member 39 that is affixed to it inany known manner.

As is typical with two-cycle crankcase compression engine practice, thecrankcase chambers 38 associated with each of the cylinder bores 35 aresealed relative to each other in an appropriate manner. A fuel-aircharge is delivered to each of the crankcase chambers 28 by an inductionsystem which is comprised of an atmospheric air inlet device 40 (seealso FIGS. 2 and 3) which draws atmospheric air through an inlet 41 fromwithin the protective cowling. This air is admitted to the protectivecowling in any suitable manner.

A throttle body assembly 42 is positioned in an intake manifold 50downstream of the air inlet 41 and is operated in any known manner.Finally, the intake system discharges into intake ports 43 formed in thecrankcase member 39. Reed-type check valves 44 are provided in eachintake port 43 for permitting the charge to be admitted to the crankcasechambers 38 when the pistons 36 are moving upwardly in the cylinder bore35. These reed-type check valves 44 close when the piston 36 movesdownwardly to compress the charge in the crankcase chambers 38, as isalso well known in this art.

Fuel is added to the air charge inducted into the crankcase chambers 38by a suitable charge former. In the illustrated embodiments, this chargeformer includes fuel injectors 45, each mounted in a respective branchof the intake manifold downstream of the respective throttle valve 42.The fuel injectors 45 are preferably of the electronically operatedtype. That is, they are provided with an electric solenoid that operatesan injector valve so as to open and close and deliver high-pressure fueldirected toward the intake port 43.

Fuel is supplied to the fuel injectors 45 under high pressure through afuel supply system, indicated generally by the reference numeral 46.This fuel supply system 46 includes a fuel tank 47 which is positionedremotely from the outboard motor 21 and preferably within the hull ofthe watercraft 30 propelled by the outboard motor 21. Fuel is pumpedfrom the fuel tank 47 by means of a fuel pump 48, which may beelectrically or otherwise operated. This fuel then passes through a fuelfilter 49, which preferably is mounted within the power head of theoutboard motor 21. Fuel flows from the fuel filter 49 through a conduitinto a fuel vapor separator 51, which includes a float controlled valvefor controlling the level of fuel in the fuel vapor separator 51. Anyaccumulated vapor will condense, and excess vapor pressure can berelieved through a suitable vent (not shown).

Also mounted, preferably in the power head, is a high-pressure fuel pump53 which is driven in any known manner as by an electric motor ordirectly from the engine 22. This fuel pump 53 draws fuel from the fuelvapor separator 51 through a conduit 52 and delivers fuel under highpressure to a fuel rail 54 through a conduit 55. The fuel rail 54 serveseach of the injectors 45 associated with the engine.

A return conduit 56 extends from the fuel rail 54 to a pressureregulator 57. The pressure regulator 57 controls the maximum pressure inthe fuel rail 54 that is supplied to the fuel injectors 45. This is doneby dumping excess fuel back to the fuel vapor separator 51 through areturn line 58. The regulated pressure may be adjusted electricallyalong with other controls, as will be described.

The fuel-air charge which is formed by the charge-forming and inductionsystem as thus far described is transferred from the crankcase chambers38 to combustion chambers, indicated generally by the reference numeral59, of the engine. These combustion chambers 59 are formed by the headsof the pistons 36, the cylinder bores 35, and a cylinder head assembly61 that is affixed to the cylinder block 34 in any known manner. Thecharge so formed is transferred to the combustion chamber 59 from thecrankcase chambers 38 through one or more scavenge passages 62.

Spark plugs 63 are mounted in the cylinder head 61 and have their sparkgaps 64 extending into the combustion chambers 59. The spark plugs 63are fired by a capacitor discharge ignition system (not shown) . Thisoutputs a signal to a spark coil which may be mounted on each spark plug63 for firing the spark plug 63 in a known manner.

The capacitor discharge ignition circuit is operated, along with certainother engine controls such as the regulated fuel pressure, by an enginemanagement ECU, shown schematically and identified generally by thereference numeral 66.

When the spark plugs 63 fire, the charge in the combustion chambers 59will ignite and expand so as to drive the pistons 36 downwardly. Thecombustion products are then discharged through exhaust ports 67 formedin the cylinder block 34. These exhaust gases then flow through anexhaust manifold, shown in FIG. 4 and identified by the referencenumeral 68. The exhaust gases then pass downwardly through an opening inthe guide plate 24 to an appropriate exhaust system (to be describedlater) for discharge of the exhaust gases to the atmosphere.Conventionally, the exhaust gases are discharged through a high-speedunder-the-water discharge and a low-speed, above-the-water discharge.The systems may be of any type known in the art.

The engine 22 is water cooled, and for this reason, the cylinder block34 is formed with a cooling jacket 69 to which water is delivered fromthe body of water in which the watercraft is operating. Normally, thiscoolant is drawn in through the lower unit 28 by a water pump positionedat the interface between the lower unit 28 and the drive shaft housing27 and driven by the drive shaft. This coolant also circulates through acooling jacket formed in the cylinder head 61. After the water has beencirculated through the engine cooling jackets, it is dumped back intothe body of water in which the watercraft is operating. This is done inany known manner and may involve the mixing of the coolant with theengine exhaust gases to assist in their silencing. This will also bedescribed later.

Although not completely shown in the drawings, the engine 22 is alsoprovided with a lubricating system for lubricating the various movingcomponents of the engine 22. This system may spray fuel into the intakepassages in proximity to the fuel injector nozzles 45 and/or may deliverlubricant directly to the sliding surfaces of the engine 22. Thislubricant is supplied from a tank 70 mounted adjacent the air inletdevice 40 (FIG. 3).

Referring now primarily to FIGS. 4 and 5, the exhaust system fordischarging the exhaust gases to the atmosphere will be described. Ashas been noted, the exhaust manifold 68 communicates with an exhaustpassage, indicated by the reference numeral 71, that is formed in thespacer or guide plate 24. An exhaust pipe 72 is affixed to the lower endof the guide plate 24 and receives the exhaust gases from the passage71, as shown by the arrows 73.

The exhaust pipe 72 depends into an expansion chamber 74 formed withinthe outer shell 75 of the drive shaft housing 27. This expansion chamber74 is defined by an inner member which has a lower discharge opening 76that communicates with an exhaust chamber 77 formed in the lower unit 28and to which the exhaust gases flow.

A through-the-hub, high speed, exhaust gas discharge opening 78 isformed in the hub of the propeller 29 and the exhaust gases exit theoutboard motor 22 through this opening below the level of water in whichthe watercraft 30 is operating when traveling at high speeds. Inaddition to this high speed exhaust gas discharge, the outboard motor 21may be provided with a further above-the-water, low speed, exhaust gasdischarge (not shown). As is well know in this art, this above-the-waterexhaust gas discharge is relatively restricted, but permits the exhaustgases to exit without significant back pressure when the watercraft 30is traveling at a low rate of speed or is idling, and thethrough-the-hub exhaust gas discharge 78 will be deeply submerged.

As has been previously noted, the cooling water from the engine coolingjacket 69 may also be mixed with the exhaust gases. To accomplish this,the guide plate 24 is provided with a cooling jacket 79 which extendsaround the exhaust passage 71 and into which the spent cooling waterfrom the engine 22 is returned. This water is then drained through oneor more drain openings 81 formed in the lower surface of the guide plate24. These openings 81 communicate with a water jacket 82 which is formedin the space 83 existent between the outer shell of the expansionchamber 74 and the inner surface of the drive shaft housing outer shell75. This water flows in the direction of the arrows 85.

Finally, a horizontally extending wall 86 formed at a lower portion ofthe drive shaft housing 27 is provided with one or more water dischargeopenings 87. The water flows through these openings 87, as alsoindicated by the arrows 85, so as to mix with the exhaust gas flow 73and be discharged back into the body of water in which the watercraft isoperating.

Thus, the existence of the cooling jacket 83 around the expansionchamber 74 provides silencing and cooling. If desired, a cooling jacketmay also be formed around the exhaust manifold 68, and this coolingjacket is formed, as shown primarily in FIG. 4, by a cover plate 88 thatis affixed to the side of the cylinder block 34 and which defines acooling jacket 89, as well as a portion of the exhaust manifold 68.Coolant is delivered to this cooling jacket 89 from the engine coolingjacket 69 in an appropriate manner. This water is also then dischargedto the guide plate cooling jacket 79.

It has been noted that the ECU 66 controls the capacitor dischargeignition circuit and the firing of the spark plugs 63. In addition, theECU controls the fuel injectors 45 so as to control both the beginningand duration of fuel injection and the regulated fuel pressure, asalready noted. The ECU 66 may operate on any known strategy for thespark control and fuel injection control 45, although this systememploys an exhaust sensor assembly indicated generally by the referencenumeral 91 constructed in accordance with the invention.

So as to permit engine management, a number of sensors are employed.Some of these sensors are illustrated either schematically or in actualform, and others are not illustrated. It should be apparent to thoseskilled in the art, however, how the invention can be practiced with awide variety of control strategies other than or in combination withthose which form the invention.

The sensors as shown primarily in FIG. 1 include a crankshaft positionsensor 90 which senses the angular position of the crankshaft 23 andalso the speed of its rotation. A crankcase pressure sensor 92 is alsoprovided for sensing the pressure in the individual crankcase chambers38. Among other things, this crankcase pressure signal may be employedas a means for measuring intake air flow and, accordingly, controllingthe amount of fuel injected by the injector 45, as well as its timing.

A temperature sensor 93 may be provided in the intake passage downstreamof the throttle valve 42 for sensing the temperature of the intake air.In addition, the position of the throttle valve 42 is sensed by athrottle position sensor 94. Engine temperature is sensed by a coolanttemperature sensor 95 that is mounted in an appropriate area in theengine cooling jacket 69. An in-cylinder pressure sensor 96 may bemounted in the cylinder head 61 so as to sense the pressure in thecombustion chamber 59. A knock sensor 97 may also be mounted in thecylinder block 34 for sensing the existence of a knocking condition.

Certain ambient conditions also may be sensed, such as atmospheric airpressure by a sensor 98, intake cooling water temperature, as sensed bya sensor 99, this temperature being the temperature of the water that isdrawn into the cooling system before it has entered the engine coolingjacket 69.

In accordance with some portions of the control strategy, it may also bedesirable to be able to sense the condition of the transmission fordriving the propeller 29 or at least when it is shifted into or out ofneutral. Thus, a transmission condition sensor 100 is mounted in thepower head and cooperates with the shift control mechanism for providingthe appropriate indication.

Furthermore, a trim angle sensor 101 is provided for sensing the angularposition of the swivel bracket 31 relative to the clamping bracket 33.

Finally, the engine exhaust gas back pressure is sensed by a backpressure sensor 102 that is positioned within the expansion chamber 74which forms part of the exhaust system for the engine and which ispositioned in the drive shaft housing 27.

The types of sensors which may be utilized for the feedback controlsystem provided by the ECU 66 are only typical of those which may beutilized in conjunction with the invention. As has been noted, theinvention deals primarily with the oxygen sensor assembly 91 and itsconstruction and the way in which exhaust gases are delivered to it. Forthat reason, further details of the description of the components of theengine and outboard motor that have no particular importance inconjunction with the understanding of the construction and operation ofthe oxygen sensor assembly have been omitted.

To be able to understand the construction and operation of the oxygensensor assembly 91, it is also necessary to identify the variouscylinders of the engine since, at least in some embodiments, the oxygensensor assembly 91 is associated with more than one cylinder of theengine 22, for reasons which will become apparent. In order to permitthis description to be more clearly understood, the cylinders of theengine 22 have been numbered from top to bottom as cylinder 1, cylinder2 and cylinder 3. In conjunction with the description of the exhaustsensor assembly 91, therefore, certain of the components which have beenemployed to describe the actual physical parts of the cylinders may alsobe identified as associated with a particular cylinder through the useof a suffix indicating the cylinder number to the individual partnumber.

The cylinders are numbered from top to bottom with cylinder no. 1 beingjuxtaposed to a flywheel magneto assembly 103 that is affixed to theupper end of the crankshaft 23 in any well known manner. This flywheelmagneto assembly 103 supplies electrical power for the aforenotedcapacitor discharge ignition system. In addition, it may be providedwith a ring gear 104 that cooperates with an electrically operatedstarter motor 105 (FIG. 3) that is affixed to one side of the cylinderblock 34.

The sensor assembly 91 has a construction as best shown in FIGS. 6 and7, although its interaction with the engine will be described later byreference to other figures. The sensor assembly 91 is comprised of anouter housing assembly, indicated generally by the reference numeral106, and which is comprised, in this embodiment, of an outer housingpiece 106a that defines a relatively large accumulator volume 107.

A sensor element, in this case an oxygen sensor, indicated generally bythe reference numeral 108, has its sensing portion 109 mounted within afitting 111 which, in turn, has a threaded connection 112 with the outerhousing element 106a, so that the sensor portion 109 extends into theaccumulator chamber 107. However, the sensor portion 109 is protected bymeans of a protecting shell 113 that is fitted onto a tubular projection114 of the mounting fitting 111. A plurality of openings 115 are formedin the shell 113 so as to permit the communication of exhaust gases withthe sensor portion 109, but also to protect the sensor portion 109 fromdamage.

The sensor portion 109 is formed as a platinum-plated glass tube havinga hollow center 116. An electrical heater 117 extends in the hollowcenter 116 along the centerline 118 of the sensor 108 and whichcommunicates with the ECU 66 through a shielded conductor 119. As isknown, the element 109 will output a signal indicative of oxygen contentin the exhaust gas, and thus provides an indicator whether the fuel/airmixture is stoichiometric or not. The actual constituency of the sensor109 may be of any desired type utilized in this control art. Theimportant features of the invention is that the sensor is positioned inthe accumulator chamber 107 in such a manner and is of such a size thatit occupies substantially less than one-half of the volume of theaccumulator chamber 107. This ensures that the gas actually sensed bythe sensor element 109 will be representative of the actual combustionproducts of the engine.

In this and in certain other embodiments, the exhaust gases orcombustion products are delivered to the accumulator chamber 107 in atimed relationship from one cylinder of the engine. In this particularembodiment, the cylinder which supplies the exhaust gases to theaccumulator chamber 107 is cylinder no. 2. The way in which this isaccomplished will now be described by primary reference to FIGS. 6-10,although the structure also appears in certain of the other figures.

A first or inlet conduit 121 opens into the accumulator chamber 107 andhas an inlet port 122 which opens into the cylinder bore 35-2 of the no.2 cylinder. This inlet port 122 is disposed at a point approximatelyequal to the point where the exhaust port 67-2 is opened as the piston36-2 is moving down at the end of the expansion and the beginning of thescavenge stroke, as shown in FIG. 9. The direction of piston 36-2 travelis indicated by the arrow thereon. Thus, under the condition as shown inFIG. 9, exhaust or combustion gases will flow from the combustionchamber 59-2 into the accumulator chamber 107 through a port 123 formedat the end of the conduit 121, and as shown by the arrow 124. It shouldbe noted that this communication is open at the time when the piston36-2 first slides past the communication port 122, and this occurssubstantially at the end of the combustion and expansion phase andbefore the scavenge ports 62-2 of this cylinder (2) are opened.

A further and exhaust conduit 125 extends from a point in theaccumulator chamber 107 that is, in this embodiment, spaced further fromthe sensor element 109 than the port 123 from cylinder no. 2. Thiscommunication passageway 125 has an inlet port 126 which opens into theaccumulator chamber 107 and a discharge port 127 which communicates withcylinder no. 1, as shown in FIG. 8.

It should be noted that the communication port 127 intersects thecylinder bore 35-1 at a point adjacent where its scavenge port 62-1 willbe opened when the piston 36-1 moves downwardly. That is, the ports 122and 127 of the communication conduits 121 and 125 have a differenttiming relative to the events in the cylinders with which they areassociated. Also, it should be noted that the cylinders are out of phasewith each other, as is typical with engine practice, so as to providemore uniform firing impulses. This condition may be best seen in FIG.10, wherein the timing phase for each cylinder is depicted in relationto crankshaft rotation.

It will be seen that the cylinders 1, 2 and 3 reach top dead centerposition at 120° from each other so as to provide equal firing impulses.It will be also seen from FIG. 10 that because of the spacing of therespective port openings 122 and 127, the port opening 122 will beopened and closed for approximately equal crank angles. However, theport 127 will be opened a shorter time than that of the port 122, andclosed for a longer time than it is open. Also, the opening and closingtimes are staggered from each other, as shown in this figure, due to thedifference in timing of the individual cylinders.

Thus, beginning at the crankshaft rotation indicated by the point A inFIG. 10, cylinder no. 2 will be at a point slightly after its top deadcenter position, with the piston 36-2 moving downwardly in the cylinderbore, as shown by the arrow on the piston in FIG. 9. However, the piston36-2 will be displaced in the cylinder bore 35-2 well above the positionshown in FIG. 9 so that the port 122 will be closed and the combustionwill have just begun and the gases will be expanding. At this same time,the piston 36-1 in cylinder no. 1 will still be traveling downwardly ina direction opposite to the arrow on the piston shown in FIG. 8, and thepiston will be approximately in the position shown in FIG. 8, with theport 127 just about to open. At this time, due to internal leakage thepressure of the gases trapped in the chamber 107 will have fallen to apoint A, as shown in the graph of FIG. 10.

Upon continued rotation of the crankshaft 23, the port 127 will open,while the port 122 is still closed, and the pressure in the accumulatorchamber 107 will fall and the gases will flow from the chamber 107 tothe cylinder bore 351. At this point in time, the pressure in thecylinder bore 35-1, and specifically in its combustion chamber 59-1,will be substantially lowered because the exhaust port 67-1 will havebeen open for some time and the scavenge port 62-1 will have just openedalong with the opening of the port 127. Thus, the pressure in theaccumulator chamber 107 will be higher than this pressure and flow willoccur in the direction of the arrow 125a, as indicated in FIG. 8. FIG.10 also shows the drop-off of pressure in the accumulator chamber.

This movement continues with the piston 36-1 of cylinder 1 reaching itsbottom dead center position and then moving upwardly, as shown by thearrow on the piston in FIG. 8, in a direction to close the scavenge port62-1 and eventually the port 127 communicating with the accumulatorchamber 107. However, before the port 127 is closed, the piston in 36-2in cylinder no. 2 will have moved past the port 122 and it will beopened at approximately the same time the exhaust port 672 of thiscylinder opens. As a result, the high pressure gases from the combustionchamber 59-2, which have not had a chance to dissipate through fullopening of its exhaust port 67-2, will flow through the conduit 121, asshown by the arrow 124, into the accumulator chamber 107.

When the port 122 does open at the point B, then the pressure in theaccumulator chamber 107 will build up quite rapidly, and the accumulatorchamber 107, which has been purged by the flow when both ports 122, 127were open, will be charged with the fresh combustion products fromcombustion chamber 59-2. This build-up pressure occurs until andslightly after the point C when the port 127 closes. This operationcontinues, although the pressure in the accumulator chamber 107 willthen begin to fall, due to the exhaust of gases as its exhaust port 67-2is opened, until this port again closes at the crank angle D.

Hence, the time period C to D is a time period when the exhaust gases inthe chamber 107 will represent the instantaneous condition in cylinderno. 2 and the ECU 66 is programmed so as to read the output from thesensor element 109 during this time period. Thus, a very good reading ofexhaust gas constituents combustion process can be measured at thistime, and then appropriate feedback control initiated by the ECU 66 toprovide the appropriate air/fuel ratio and exhaust emission control.

In the embodiment thus far described, the exhaust condition sensorassembly 91 has received its inlet of exhaust gases from cylinder no. 2,and exhaust gases were discharged from the accumulator chamber 107 tocylinder no. 1. FIG. 11 shows another embodiment of the inventionwherein the sensor assembly 91 receives exhaust gases from cylinder no.1 and the exhaust gases are discharged not directly back to anothercylinder, but back to the induction system, and specifically the intakemanifold 50 at a point downstream of the throttle valve of one of theintake runners. This throttle valve is shown in this figure and isidentified by the reference numeral 151. Thus, the supply conduit 121has its inlet port 122 in communication with the cylinder bore 35-1 at apoint substantially the same as the communication passageway withcylinder bore 35-2 of the previously described embodiment. The dischargepassageway 125, however, has a discharge end 152 in communication withthe intake passage of the manifold 50 downstream of the throttle valve151. Thus, the exhaust gases will be bled back in and mixed with theintake charge. This may, in fact, be utilized to provide a limitedamount of exhaust gas recirculation. The operation of this embodimentshould be apparent from the foregoing description and, for that reason,further description of this embodiment is not believed to be necessaryto permit those skilled in the art to practice the invention.

FIGS. 12 and 13 show another embodiment which is similar to theembodiment of FIG. 11, and the overall engine construction is similar tothe embodiment of FIGS. 1-10. For that reason, where components of thisembodiment are the same or substantially the same as those previouslydescribed, they have been identified by the same reference numerals.

In this embodiment, the accumulator chamber 107, and specifically itsdischarge conduit 125, is communicated with a crankcase chamber of theengine. The conduit 121 has its port 122 communicating with the cylinderbore 35-1 in the manner previously described. In addition, a pair ofone-way check valves, indicated by the reference numerals 171 and 172,are provided in the inlet conduit 121 and exhaust conduit 125,respectively. These check valves 171 and 172 permit flow only in thedirection of the arrows illustrated, and, therefore, it will be ensuredthat reverse flow cannot occur. That is, the accumulator chamber 107will always be charged from the cylinder bore 35-1 and will dischargealways to the crankcase chamber. No reverse flow will be permittedbecause of the check valves 171 and 172.

FIGS. 14-16 show another embodiment of the invention which is generallysimilar to those embodiments thus far described, and where thecomponents are the same or substantially the same, they have beenidentified by the same reference numerals and will only be describedagain as is necessary to understand the construction and operation ofthis embodiment.

In this embodiment, the sensor assembly 91, and specifically its housing106a, is mounted to the cylinder block 34 by means of a mounting bracket201. The mounting bracket 201 is appropriately affixed to the cylinderblock.

In this embodiment, like those of FIGS. 11 and 12 and 13, the pressuresupply conduit 121 for the accumulator chamber 107 has its inlet port122 in registry with the first cylinder bore 35-1 at a location aspreviously described. With this embodiment, the discharge conduit 127extends in part through the cylinder block 34 and terminates in adischarge opening 202 that communicates with the exhaust manifold 68,and specifically the portion of the exhaust manifold adjacent theexhaust port 67-1 of cylinder no. 1. In other regards, this embodimentis the same as those previously described and, for that reason, furtherdescription of this embodiment is not believed to be necessary to permitthose skilled in the art to practice the invention.

FIGS. 17-20 show a sensor assembly 91 constructed in accordance with yetanother embodiment of the invention. Like those embodiments previouslydescribed, many components of this embodiment are the same as thosedescribed previously and, for that reason, components which are the samehave been identified by the same reference numerals and will not bedescribed again, except insofar as is necessary to understand theconstruction and operation of this embodiment.

Like the embodiment of FIGS. 14-16, the sensor housing 106a is mountedon the cylinder block 34 by a mounting bracket which has a slightlydifferent configuration than that of that embodiment, but since it isthe same in function, it has been indicated by the same referencenumeral (201). In this embodiment, however, there is provided only aninlet conduit 121 which has its inlet port 122 in communication with thecylinder bore 35-1 at a point adjacent that corresponding to the openingof the exhaust port for this cylinder. In this embodiment, there is,however, no discharge conduit. Thus, the construction is simpler butwill not provide as accurate an indication of each firing of thecylinder. However, the leak-down of pressure that occurs will causesufficient fluctuation to provide good signals and, as noted above, thisembodiment is simpler than those previously described.

FIGS. 21 and 22 illustrate another embodiment which has the simplicityof the embodiment of FIGS. 17-20, in that it only has one communicationpassageway, but will also ensure that the accumulator chamber 107 willreceive a charge that is indicative of cycle-to-cycle operations. Inthis embodiment, the sensor assembly 91 is mounted directly on thecylinder head 61 and communicates with an internal passageway 221 formedtherein, which communicates with one of the combustion chambers 59, inthis instance the combustion chamber 59-1, associated with the no. 1cylinder. Thus, there will be flow into and out of the accumulatorchamber during the entire engine cycle.

In all of the embodiments as thus far described, the sensor assembly 91has been positioned and constructed so as to receive the combustionproducts directly from the respective combustion chamber 59. Next willbe described a series of embodiments wherein the sensor assembly 91contacts the combustion products at a position in the exhaust system. Ineach of these embodiments, the structure of the sensor 108, per se, isthe same as that previously described. However, the accumulator chamber,which will be identified by a different reference numerals, is formedintegrally within either the engine 22 or another component of theoutboard motor.

Referring first to the embodiment of FIG. 23, in this embodiment, theguide plate 24 is provided with an integral accumulator chamber 241which is formed on one side of the exhaust passage 71 therethrough. Thisdefines a volume into which the sensor element and its surroundingprotective sleeve 113 passes. This chamber 241 is closed by a mountingplate 242 onto which the fitting 111 of the sensor element is threadedso as to provide a good support and yet one that would be wellinsulated. The sensor element 109 is not shown in this figure, but itmay be the same as that shown in FIG. 7.

The accumulator chamber 241 communicates with the exhaust passage 71through an opening 243. Thus, exhaust gases can flow into theaccumulator chamber 241 through the opening 243.

A smaller vertically downwardly extending passage 244 extends throughthe guide plate 24 and into the exhaust expansion chamber 74 so that theexhaust gases may discharge. Also, this configuration permits any liquidwhich may condense in the accumulator chamber 241 also to drain into theexpansion chamber 74.

This figure also shows small water drain openings 245 that extend fromthe spacer plate cooling jacket 79 into the expansion chamber 74 so thatsome water will be mixed directly with the exhaust gases and thusprovide additional silencing and cooling therefor.

FIG. 24 shows another embodiment which is basically the same as theembodiment of FIG. 23. This embodiment, however, lacks the drain passage244 and provides a smaller communicating port 251 that communicates theaccumulator chamber 241 with the guide plate exhaust passage 71.

Another mounting arrangement for the sensor 108 is shown in FIG. 25, andin this embodiment, the engine exhaust cover plate 88 is provided withan integral accumulator chamber 271 which communicates with the exhaustmanifold 68 adjacent one of the exhaust ports 67 through a restrictedopening 272. Again, the construction of the sensor 108 is the same asthat shown in FIG. 7 and, accordingly, this structure will not bedescribed again.

This embodiment also employs a drain and discharge passageway 273 thathas a discharge end 274 formed in the exhaust manifold 68 and which willcreate a pressure difference for flow through the accumulator chamber271 and will also permit liquids to drain away from the sensor element109.

Next will be described a series of embodiments which are generally thesame as the embodiment of FIGS. 1-10 in that the accumulator chamber 107communicates with two cylinders of the engine but with different timingso as to promote a one-way flow through the accumulator chamber 107. Theconnected cylinders in these embodiments are different from those shownin the embodiment of FIGS. 1 and 10, but because this is the onlydifference in the basic engine construction and connection of theelements, those elements which are the same or substantially the same asthose previously described have been identified by the same referencenumerals and will be described again only insofar as is necessary tounderstand and practice these embodiments.

In addition to the aforenoted difference, these embodiments alsoincorporate an arrangement for ensuring against contamination of theexhaust sensor 109 and other improvements in the sensor unit 91 itself.

Referring first to the embodiment of FIG. 26, it will be seen that theinlet conduit 121 that supplies exhaust gases to the sensor assembly 91,and specifically the accumulator chamber 107 thereof, extends from no. 1cylinder. Therefore, the inlet port 122 is disposed so that it will belocated at a point in the cylinder bore 35-1 that is disposedimmediately adjacent the top edge of the respective exhaust port 67-1 sothat it will open and close at substantially the same timing as theopening and closing of the exhaust port.

The return passage 125 extends to the cylinder bore 35-3 of cylinder no.3 and is disposed so as to be opened and closed later in this cylindercycle than the inlet opening 122. These openings are at slightlydifferent phases than the previously described embodiment and, for thatreason, the opening and closing will be described by reference to FIG.30. In the embodiment of FIGS. 1-10, cylinders 1 and 2 were 120° out ofphase from each other, and thus, the relationship between the portopenings of the ports 122 and 127, was as shown in FIG. 10. Basically,the same relationship exists between the cylinders 1 and 3 in thisembodiment where the timing of the port openings 122 and 127 are alsoshown in FIG. 30.

As may be seen, starting from the point A, when the inlet port 122 andcylinder bore 35-1 is closed because the piston is still movingdownwardly from its top dead center position, the port 127 in thecylinder no. 3 will be open and pressure will fall off in the chamber107.

This fall off in pressure occurs until the point B when the port 122 isopened by the downward movement of the piston 36-1 in the cylinder bore35-1 when the exhaust port 67-1 first opens. Hence, pressure will buildup rather rapidly up to the point C when the port 127 moves to itsclosed position. At the same time, the pressure at the port 122 willbegin to decrease because of the opening of the exhaust port and thepressure will fall off to the point D. As with the previously describedembodiment, the actual measurement by the sensor takes place in thistime period (C to D).

As may be seen from FIG. 29, in this embodiment, the inlet port 123 intothe accumulator chamber 107 is disposed at a greater distance from thesensor 109 than the earlier embodiment. In addition, the gases must flowat an angle, as shown by the line 271, to the outlet port 126. Thismovement is away from the sensor 109 and thus the sensor will beprotected against impingement from foreign particles and lubricant inthe combustion gases. In addition, any liquids that may condense in theaccumulator chamber 107 can drain out of the opened port 126 down to thelowermost cylinder so as to avoid a build-up of contamination in theaccumulator chamber. Thus, this embodiment provides the same advantagesof the embodiment of FIGS. 1-10, but also the further advantage ofbetter protection from contamination of the sensor 109.

FIG. 31 shows another embodiment of the invention, where both the inletconduit 121 and discharge conduit 125 are extended so as to protrude inpart into the accumulator chamber 107. These extending portions areindicated by the reference numerals 281 and 282, respectively. As may beseen, this causes the flow path 283 to be more acute and assist inseparation due to the circuitous path that must be followed. Inaddition, this tends to further protect the sensor 109 fromcontamination.

Another sensor configuration that is constructed to protect the sensorelement from contamination is shown in FIG. 32 and is identifiedgenerally by the reference numeral 301. This sensor 301 has the samebasic construction and operation of the sensor of FIGS. 1-10, and whichis shown in most detail in that embodiment in FIG. 6. Therefore, wherecomponents have the same construction and operation, they have beenidentified by the same reference numerals employed in that embodimentand will be described again only insofar as is necessary to understandthe construction and operation of this embodiment.

It should be noted that this embodiment also reverts to the cylinder no.2 to cylinder no. 1 connection of the embodiment of FIGS. 1-10, asopposed to the cylinder no. 1 to the cylinder no. 3 connection of theembodiment of FIGS. 26-30 and 31.

In this embodiment, protection is provided by placing an orifice plate,indicated generally by the reference numeral 302, at the discharge end123 of the conduit 121 where it enters the accumulator chamber 107. Thiscontrol orifice 302 has a restricted central opening 303 defined at thepair of conical sections 304 and 305 which in effect provide aconvergent/divergent nozzle. Therefore, the flow along a path 306 willcause some of the air to be turned, as shown at 307, which will tend toreduce the likelihood that oil particles having larger inertia can enterthe accumulator chamber 107. Thus, this slows down the flow and providesfurther assurance that the sensor 109 will not be contaminated.

FIGS. 33-37 show a still further embodiment of the invention whichconnects the sensor, indicated generally by the reference numeral 351 inthis embodiment, with the engine in the same manner as with theembodiment of FIGS. 26-30. Because of that similarity, the basic engineand its association with the sensor will not be described again, and thesame reference numerals have been applied so as to facilitate theunderstanding of the operation of this embodiment without necessitatinga further description of components which have already been described.

In this embodiment, the sensor 351 is constructed in a way so as tofurther protect the exhaust sensing element, indicated generally by thereference numeral 108, and which has a construction substantially thesame as that shown in FIG. 7. However, the protective device isconstructed in a different manner, and it is comprised of an outerhousing assembly, indicated generally by the reference numeral 352, andwhich includes a first housing piece 353 which defines a first chamber354. The conduit 121 has an extending portion 355 which extends into thechamber 354 and which has a plurality of perforate openings 356 whichcommunicate the discharge end 123 with the chamber 354.

The end of the extending portion 355 is received in a counterbore 357formed adjacent the inner end of the chamber 354 and from which aU-shaped passage 358 extends. The passage 358 terminates in acounterbore 359 in which the inlet end 126 of the conduit 125 is pressfit.

The chamber 354 is formed by a bore 361 that receives a closure plug 362which is fitted around the inlet tube extension 355.

The sensor 108, and specifically its outer protecting sleeve 113, whichhas the openings 115, extends into a further accumulator chamber 364formed by an opening 363 in the housing piece 353 and which is closed bya closure plug 365. A small orifice 366 communicates the accumulatorchamber 364 with the accumulator chamber 354. These two chambers and, infact, either one of them, has a volume that is more than one-half of thevolume of the sensor element 109 itself.

The orifice 366 is surrounded by a conical surface 367 so that anylubricant which may enter the accumulator chamber 364 through theorifice 365 will condense, collect and drain back into the accumulatorchamber 354.

In a similar manner, a drain port 368 is formed in the lower wall 361 ofthe accumulator chamber 354 and communicates with the conduit opening359. The lower surface of this drain opening 368 is also formed with aconical surface 369 so as to assist in the assurance that lubricant orother foreign materials cannot damage the sensor assembly 109.

A sensor arrangement constructed in accordance with another embodimentis illustrated in FIG. 38. This embodiment differs from the embodimentof FIGS. 36 and 37 only in that the conduit 125 is not provided with theextension 355 or the apertures 356 and thus freely communicates with thechamber 354. However, this still provides the circuitous flow path andthe protection of the sensor 108 from foreign contaminants. Because ofits other similarities to the earlier embodiment, it is believed that afurther description of this embodiment is not necessary to permit thoseskilled in the art to practice the invention.

FIG. 39 shows yet another embodiment which is similar to the embodimentsof FIGS. 36 and 37 and of FIG. 38. In this embodiment, however, theaccumulator chamber 354 is eliminated and the supply conduit 121 has anextending portion 401 that extends through an elongated bore 402 formedin the housing piece 353. A first port 403 extends through once side ofthe tube to the accumulator chamber 364 in which the sensor 108 ispositioned and permits the exhaust gases to flow through this andthrough the restricted passageway 366, as the previously describedembodiment.

In addition, a further passageway 404 in the tube end 401 communicateswith the drain passageway 368 for return of drained or accumulatedfluids. Again, the volume of the accumulator chamber 364 issubstantially greater than half of the volume displaced by the sensor109.

FIG. 40 shows another embodiment which is similar to the embodiments ofFIGS. 36 and 37, FIG. 38 and FIG. 39. This embodiment employs theaccumulator chamber 354 as the embodiments of FIGS. 36 and 37 and 38,but incorporates a further arrangement for providing a circuitous flowpath therethrough that will help in the separation of lubricant andother foreign contaminants. Thus, the inlet conduit 121 is formed withan extending portion 451 that terminates at an end 454 in the chamber354 which is spaced from the restricted opening 366 which communicatesthe accumulator chamber 354 with the accumulator chamber 364.

In addition, a discharge tube 455 is pressed into a counterbore 456 inthe housing piece 353 and has its inlet end 457 spaced from and offsetfrom the outlet end 454 of the conduit extension 451. As a result, therewill be a circuitous flow path that will assist in the separation of oiland contaminants.

FIG. 41 illustrates an embodiment which is basically the same as theembodiment of FIGS. 36 and 37. Therefore, the components of thisembodiment which are the same as that embodiment have been identified bythe same reference numerals and will not be described again.

In this embodiment, the housing piece 353 is provided with a drainaccumulation chamber 471 into which the gases flow from the passage 358and also from the drain opening 368 and chamfered surface 369. The lowerportion of the drain chamber 471 is provided with a drain opening 472normally closed by a fitting 473. The fitting 473 may be removed fordraining of accumulated fluids. The other cylinder of the engine(cylinder no. 3 in this embodiment) communicates with the drain chamber471 or some other area upstream of the drain chamber 471.

The embodiments for protecting the sensor 108 from contamination thusfar described have done this by primarily mechanical means. Now will bedescribed several embodiments of the invention where this protection isachieved by means in addition to mechanical means. In these embodiments,heat is maintained in the accumulator chamber 107 in a variety offashions. This provides two purposes. First, the sensor element 109 willbe maintained at an elevated temperature and one which keeps it at itsoperating temperature. As know in this art, most exhaust sensors do notbecome fully operative until they reach an operating temperature that isrelatively high. Thus, by maintaining heat in the chamber 107 and on thesensor element 109, it is possible to ensure good operation of thesensor. In addition, by keeping the temperature high, the likelihood oflubricant condensing in the accumulator chamber 107 is avoided.

Referring first to the embodiment of FIG. 42, the sensor is providedwith an insulating outer housing, indicated generally by the referencenumeral 501, which surrounds the housing 106a of the embodiment likethat shown in FIG. 6, with an insulating layer, indicated generally bythe reference numeral 502. As seen best in the enlarged portion of FIG.42, the insulating layer 502 comprises a thick insulating layer 503formed from a suitable material and a thin protective covering 504.Aside from this, this embodiment operates and functions the same as theembodiment of FIG. 6. For that reason, further description of thisembodiment is not believed to be necessary to understand theconstruction and operation.

FIG. 43 shows another embodiment which is basically the same as theembodiment of FIG. 42. However, this embodiment additionally provides anelectrical heating element, indicated by the reference numeral 531,within the accumulator chamber 107. This heating element 531 not only isin heat exchanging relationship with the outer housing 106a, but alsoextends around the sensor 109 and its protective sleeve 113.

The heating element 531 receives electrical power from a battery 532 andthus maintains the elevated temperature so as to provide oil protectionand also to maintain a high temperature for good operation of the sensor108.

FIG. 44 shows another embodiment which maintains heat by providing heatinsulating couplings 551 and 552 between the conduits 121 and 125 andthe adjacent engine structure. Hence, heat in the accumulator chamber107 cannot be easily transmitted away from the chamber through themetal-to-metal connection of the previously described embodiments.

FIGS. 45 and 46 relate to the embodiment of the present invention shownin FIGS. 1-10 and supplement the disclosure of FIGS. 8-10. Correspondingelements are identified using the same reference number. FIG. 45 is acombination of FIGS. 8 and 9 and illustrates the timing of the pistons36-1, 36-2 within cylinders 35-1, 35-2 in relation to the respectiveinput ports 122, 127 leading to the oxygen sensor assembly 91.Specifically, as the piston 36-2 descends within cylinder no. 2, thesensor input port 122 opens at point B, at approximately the same timethat the exhaust port 67-2 opens. This allows combustion products fromthe combustion chamber 59-2 to enter the accumulator chamber 107surrounding the oxygen sensor 108 causing the pressure in theaccumulator chamber 107 to build up quite rapidly. Because of theexpansion of the gases within cylinder no. 2, and the opening of theexhaust port 67-2, the pressure therein, shown as P2 in FIG. 46, isdecreasing. However, the pressure within cylinder no. 2 is higher thanthe pressure in cylinder no. 1 between the points B and C as best shownin FIG. 46. This causes exhaust gates to flow from the combustionchamber 59-2 into the combustion chamber 59-1 until the sensor outletport 127 closes. The point C at which the outlet port 127 closes willoccur when the piston 36-1 ascends upward sufficiently toward its topdead center position to cover the outlet port 62-1. The upward movementof the piston 36-1 compresses the gases within the combustion chamberand results in a pressure peak indicated by the line P1 in FIG. 46. TheECU 66 is programmed to read the output from the sensor element 109 at atime between points C and D.

A further embodiment is shown in FIGS. 47-49 which is generally the sameas the embodiment of FIGS. 1-10 in that the accumulator chamber 107communicates with two cylinders of the engine. Elements which are thesame or substantially the same as those previously described have beenidentified by the same reference numerals, and will be described againonly insofar as is necessary to understand and practice these furtherembodiments.

This embodiment incorporates a protective cover 600 for guarding againstpossible damage to the oxygen sensor assembly 91 and its associatedconduits 121, 125. The cover 600 may be formed of any suitable materialsuch as aluminum or high-temperature plastic and includes a pair ofoutwardly extending flanges 602 fastened to corresponding outwardextensions 603 of the engine block 34 with bolts 604. The cover 600 isconfigured to conform to the shape of the sensor assembly 91 andconduits 121 and 125. More specifically, the cover 600 comprises agenerally horizontal portion 606 adapted to extend generally around thehousing 106a, containing the accumulator chamber, sensor assembly 91 andthe shielded conductor 119 extending from the sensor 108. A secondvertical portion 608 extends outward to encompass the conduits 121, 125.The first and second portions 606, 608 are disposed generallyperpendicular to one another, and provide a space 610 therewithin forthe oxygen sensor assembly 91. A hole 607 is provided in one end of thecover 600 for accommodating insertion of the shielded conduit 119.

FIGS. 50a and 50b show another embodiment wherein the engineconstruction and oxygen sensor arrangement are similar to the embodimentof FIGS. 1-10. Again, where components of this embodiment are the sameor substantially the same as those previously described, they have beenidentified by the same reference numerals.

In this embodiment, the sensor assembly 91 is protected from possibledamage and the overall engine structure is made smaller by mounting theoxygen sensor assembly 91 in a recess formed between adjacent cylindersof the engine block 34. As can be seen by a comparison with FIG. 4, theinlet and outlet conduits 121, 125 include shorter horizontal portionsleading to the respective cylinders. The housing 106a of the oxygensensor assembly 91 fits within a recess formed between the cylinders 1and 2. The overall engine construction is thus made smaller, and thesensor assembly 91 is less subject to damage from outside forces becauseit is protected by the linkage 612 for the throttle 614. In this regard,the outward projection of the linkage 612 is indicated by dashed line616.

FIGS. 51 and 52 illustrate a further embodiment wherein an oxygen sensorassembly 618 is mounted integrally with the cylinder block 34 and thusthe overall structure is made more durable and compact. The main portionof the sensor 618, is defined by a housing 620 formed from a solid blockof material and mounted to the cylinder block 34 with bolts 622. Thehousing 620 has machined therein an accumulator chamber 107 for housingthe sensor element 109. In the embodiment illustrated, the housing 622is mounted proximally between cylinders 1 and 2.

The inlet conduit to the accumulator chamber 107 is defined by a firstportion 624 formed in the housing 622 angled upward and toward cylinderNo. 1 35-1 and a second portion 626 formed in the engine block 34 andhaving approximately the same angle as the first portion 624. The secondportion 626 extends into the first cylinder 35-1 and terminates at aninlet port 628.

The outlet conduit of the accumulator chamber 107 is defined by a shortsubstantially vertical first portion 630 formed in the sensor housing620, and an elongated second vertical portion 632 formed in the engineblock 34. The first and second portions 630, 632 extend generallyvertically downward from the accumulator chamber 107 toward cylinder 3.The second portion 632 may be machined directly in the cooling jacket orin an outwardly projecting rib 634 cast on the engine block 34. A shorthorizontal extension 636 joins the lower end of the second portion 632to the cylinder wall 35-3. The short horizontal portion 636 terminatesin the outlet port 638.

In this embodiment, the exhaust gases flow from cylinder 1 past oxygensensor assembly 618 to cylinder 3. Optionally, a bracket 640 may bemounted on the engine block 34 with bolts 642 provide added strength asneeded. Of course, other variations may be utilized.

FIGS. 53-55 illustrate variations on the oxygen sensor arrangement ofthe present invention wherein lubricant contamination of the sensorelement is reduced. FIG. 53 shows an oxygen sensor assembly 648 arrangedin accordance with another embodiment of the invention. Like theembodiments previously described, many components of this embodiment arethe same and, for that reason, will not be described again exceptinsofar as is necessary to understand the construction and operation ofthis particular embodiment. The oxygen sensor generally indicated by thereference numeral 108 has its sensing portion 109 mounted within afitting 111 so that the sensing portion 109 extends into the accumulatorchamber 107.

The sensor portion 109 is protected by a protective sleeve 650 fittedonto a tubular projection (not shown) of the mounting fitting 111. Theprotective sleeve 650 is defined by a generally cylindrical wall portion652 having a series of vent openings 654. The protective sleeve 650includes a non-vented barrier surface 656 on its lower generatrix facingupstream of the inlet port 123. The barrier surface 656 helps reduce theamount of lubricant which may directly contact the sensor element 109.Furthermore, the gas flow 658 within the accumulator chamber 107 isdirected away from the sensor element 109 by positioning of the outletport 126 further away than inlet port 123 with respect to the sensorelement 109. In this manner, the gas flow 658 is directed around theterminal end of the protective sleeve 650, and out the outlet port 126,without directly impinging upon the sensor element 109.

FIGS. 54 and 55 show a still further embodiment of the invention whichis similar in many respects to the embodiment shown in FIGS. 36 and 37.Again, because of the noted similarities, the basic engine design andits association with the sensor will not be described, and the samereference numerals have been used, where applicable, to indicate thesame or similar elements.

In this embodiment, the sensor 670 comprises an outer housing assembly353 defining first and second accumulator chambers 354 and 364. Theinlet conduit 121 extends into the first accumulator chamber 354 via anextending portion 355 having a plurality of perforated vent openings 356which are allowed to communicate with the first chamber 354. Theterminal end of the extending portion 355 is connected to a U-shapedpassage 358 terminating at a lower portion and a counterbore 359 intowhich the outlet conduit 125 is fitted. The largest lubricant particleswill have too much momentum to exit through the small holes 356 providedin the extending portion 355 and, therefore, will exit straight throughto the U-shaped passage 358.

The first accumulator chamber 354 communicates with the secondaccumulator chamber 364 via an orifice 366 having a conical uppersurface 367. Any lubricant accumulating in the second chamber 364 willcondense, collect, and drain back into the first accumulator chamber 354via the conical surface 367. To prevent lubricant from contaminating thesensor element 109, a protective sleeve 672, similar to the protectivesleeve 650 of FIG. 53, is provided. The protective sleeve 672 surroundsthe sensor element 109 and is defined by a solid wall portion 674 havinga plurality of openings 676. The openings 676 allow exhaust gases toenter and communicate with the sensor element 109 on the side downstreamfrom the inlet orifice 366. A lower barrier wall 678 protects the sensorfrom upstream flow of exhaust gases and thereby prevents lubricantwithin the exhaust gases from contacting the sensor element 109. Exhaustgases will travel from the first accumulator chamber 354 into the secondaccumulator chamber 364 by cyclical flow or diffusion through theorifice 366. This process prevents most contaminants from entering thesecond chamber 364. Any remaining lubricant particulate matter enteringthe second accumulator chamber 364 will tend to strike and condense ontothe solid wall 678, ultimately dripping downward back through theorifice 366. The threaded fitting 111 allows the sensor 108 to beremoved from the housing 353 so that the protective sleeve 672 can becleaned or replaced.

Two further sensor arrangements are illustrated in FIGS. 56-58, andincorporate a catalyst within the accumulator chambers and a lubricationfilter in series with the inlet conduit. With specific reference to FIG.56, a modified oxygen sensor assembly 690 is provided which is similarin many respects to that shown in FIG. 31. Because of the similaritiesto the earlier embodiment, like elements will be similarly numbered andwill not be described further herein. In general the oxygen sensorassembly 690 comprises housing 106a having the inlet conduit 121 andoutlet conduit 125 attached thereto. One end of the housing 106a has anopening for the sensor 108. The housing 106a defines the accumulatorchamber 107. The inner surface of the housing 106a is coated with acatalyst, such as platinum, which tends to react with unburnt lubricantin the exhaust gases to accelerate oxidation thereof. Thus, asubstantial amount of the lubricant which reaches the accumulatorchamber 107 will be oxidized, rather than coming into contact with thesensor element. To further prevent lubricant from contaminating thesensor element, the inlet conduit 121 terminates in a short extensionportion 694 which extends substantially upward within the accumulatorchamber 107. The extension portion 694 extends more than halfway acrossthe center line of the accumulator chamber 107, as shown, and is sopositioned to create a bending of the gas flow 696 toward the outletport 126 and away from the oxygen sensor element.

The inlet conduit 121 further incorporates a lubricant filter assembly698 therein. The lubricant filter assembly comprises a filter housing700 connected in series with the inlet conduit 121 and with the shortextension portion 694. The filter housing 700 provides a flow pathbetween the inlet conduit 121 and extension portion 694. A filterelement 702 is placed within an inner chamber 704 of the housing 700 inthe flow path of exhaust gas entering the accumulator chamber 107 and ismaintained in placed via a spring 707 and cap 708. The gas from theinlet conduit 121 enters the filter housing 700 and the inner chamber704. The filter element 702 is interposed between the chamber 704 and asecond chamber 706. The second chamber 706 is in direct communicationwith the short extension portion 694. The gas must thus flow into thechamber 704, through the filter element 702 and into the second chamber706 before reaching the accumulator chamber 107. The cap 708 threadablyengages the housing 700 to facilitate periodic cleaning and replacementof the filter element 702. A sealing member 710 has a cylindrical inneropening accommodating the spring 707, for retaining the filter element702 in place.

FIGS. 57 and 58 illustrate an oxygen sensor assembly 720 which is inmany respects similar to the embodiments of FIGS. 36, 37, and of FIGS.54-56. This embodiment differs from the previous ones only in that theinlet conduit 121 is provided with a filter 698 therein, and theaccumulator chambers are coated with a catalyst material. The sensor 720comprises a housing 353 forming the lower accumulator chamber 354, andthe upper accumulator chamber 364. The inlet conduit 121 terminates in ashort extension portion 722 having perforations or apertures 724therein. The exhaust gas passes from the apertures 724 and through theorifice 366 into the upper accumulator chamber 364. Both the upper andlower accumulator chambers 364, 354 are provided with a coating 726, 728similar to the coating provided in the embodiment of FIG. 56. Thecoatings 726, 728 act as catalysts to accelerate oxidation of lubricantand unburned fuel products present in the exhaust gas to protect thesensor element 109. A drain port 730 is formed in the lower wall of thelower accumulator chamber 354. The drain port 730 leads to the outletconduit 125.

A lubricant filter assembly 698, nearly identical to that shown in FIG.56, is installed in series between the inlet conduit 121 and the shortextension portion 722. More particularly, and as described above, thefilter assembly 698 comprises a housing 700 which attaches to therespective inlet and outlet tubes. The housing 700 includes the centralchamber 704 within which the filter element 702 is positioned. Thischamber may also be coated with a suitable catalyst material, as shown,in order to accelerate oxidation of lubricant and unburned fuelproducts. An angled passageway 732 is provided from the inlet conduit121 into the chamber 704. Exhaust gas travels through the angledpassageway 732 into the chamber 704 and through the filter element 702into the second chamber 706, whereupon the exhaust gas passes into theshort extension portion 722 and through the apertures 724 into the loweraccumulator chamber 354. The inclusion of the lubricant filter 698substantially reduces the lubricant content of the exhaust gasescontacting the sensor 108. The provision of the catalytic coatings 726and 728 within the accumulator chambers further helps to preventcontamination of the sensor element 109.

FIGS. 59-61 show another oxygen sensor assembly embodiment which issimilar to the embodiment of FIG. 16, and the overall engineconstruction is similar to the embodiment of FIGS. 1-10. For thatreason, where components of this embodiment are the same orsubstantially the same as those previously described, they have beenidentified by the same reference numerals.

In this embodiment, a modified oxygen sensor assembly 740 is mountedbetween the first and second cylinders 35-1, 35-2. An L-shaped mountingbracket 742 bolted to the cylinder block 34 is provided for thispurpose. As seen best in FIG. 60, the inlet conduit 121 opens at port122 into the first cylinder 35-1. The outlet conduit 125 opens at port127 into the exhaust manifold 68. With specific reference to FIG. 61,the oxygen sensor assembly 740 in this embodiment comprises a housing744 defining an upper chamber 746 and a lower chamber 748. The upperchamber 746 is in communication with the inlet conduit 121 via port 123.The lower chamber 748 is in communication with the outlet conduit 125via the port 126. The upper and lower accumulator chambers 746, 748 arejoined by a small orifice 750 having an upper conical surface 752adjacent thereto. Exhaust gas follows the path of arrow 754 from theinlet conduit 121 through the sensor 740 and out the conduit 125. Boththe upper and lower accumulator chambers 746, 748 are provided withcatalytic coatings 756, 758, much as was described previously withreference to FIGS. 56-58. In a preferred embodiment, the upperaccumulator chamber 746 is cylindrical in shape having an annularcatalytic coating 756 on at least a portion of its inner surface. Thecatalytic coating 758 surrounds the sensor 108 in the lower chamber 748.As exhaust gas travels along path 754 through the sensor 740, asubstantial amount of lubricant therein will be oxidized by thecatalytic coatings of the respective accumulator chambers. Furthermore,some of the lubricant within the exhaust gas will be condensed on theconical surface 752.

FIG. 62 illustrates a further embodiment of the present invention whichprovides a cooling flow around an accumulator chamber in which an oxygensensor element is disposed. More specifically, an oxygen sensor assembly760 is shown mounted between two cylinders on the cylinder head 61. Theoxygen sensor assembly 760 comprises a generally cylindrical housing 762having a pair of concentric annular walls 764, 766, defining a coolingpassage 768 therebetween. The sensor 108 extends within the innerannular wall 766. One or more ports 770 provided in the exterior surfaceof the housing 762 allow cooling water from cylinder head 61 to flowinto the annular cooling passage 768. The arrow 772 illustrates thecooling path of water flowing through the cooling passage 768. Waterdoes not enter the accumulator chamber 107, but cools the inner surfacesof the chamber 107 to help condense saturated gases and lubricantscontained within the exhaust gas. Exhaust gas enters through the inletport 774 from the combustion chamber 776 of cylinder 1. Although notshown in the cross section of FIG. 62, an outlet conduit may be providedfrom the accumulator chamber 107 to one of the other cylinders in theengine to allow the gas to pass through the accumulator chamber in asubstantially unidirectional manner. Alternatively, the outlet conduitmay communicate with the exhaust manifold in a manner describedpreviously. In yet another alternative, the flow of exhaust gasesthrough passage 774 may be bidirectional such that exhaust sales enterand exit the accumulator chamber 107 as the relative pressure in theaccumulator chamber 107 and the combustion chamber 776 changes them overtime.

FIGS. 63-69b show various inlet configurations for delivering exhaustgases to an oxygen sensor assembly in accordance with the presentinvention. It will be appreciated that certain flow patterns are morelikely to create contamination problems due to lubricants condensing inthe exhaust gas. FIG. 63 shows a conventional inlet conduit 121 having aport 122 opening perpendicular to the cylinder wall 35. The exhaust gasflow 780 typically follows a path down or up along the cylinder wall 35and then into the port 122. As the flow 780 turns the corner into theport 122, a region 782 of low pressure is created as the boundary layerseparates from the wall. This low-pressure region 782 detrimentallyencourages condensation of the lubrication therein, sometimes blockingor decreasing the flow through the port 122.

FIG. 64 illustrates a cross section of a cylinder 35 having an inletconduit 121 leading to an oxygen sensor (not shown). The inlet opening784 of the inlet conduit 121 is flared to improve the flow pattern ofexhaust gases therein and reduce undesirable condensation. This is shownin more detail in FIG. 65. As indicated, the streamlines of the gas flow788 are relatively smooth as they make the transition from thecombustion chamber into the inlet conduit 121 without forming asignificant low pressure pocket. The amount of lubricant condensation isthus reduced.

FIG. 66 illustrates a further embodiment of an inlet conduit opening 790having an outer flared portion 792 and an inner flared portion 794. Theouter flared portion 792 makes a larger angle with the longitudinal axisof the inlet conduit 121. Thus, a "stepped" flare is formed whichfurther helps to smooth the streamlines of the gas flow 796 and preventlow pressure pockets. It can be seen that the outer flared portion 792is formed in the cylinder wall 786, and partially in the cylinder block34. The inner flared portion 794 is formed exclusively in the cylinderblock 34. Alternatively, additional stepped surfaces may be added asdesired, or the opening may be formed continuously like the bell of ahorn.

FIG. 67 illustrates a still further embodiment of an inlet opening 800of an inlet conduit 121. The inlet conduit 121 in this embodimentextends at an angle to the cylinder wall 35, and the inlet opening 800is similarly angled to further smooth the gas flow 802 and reducecondensation. The inlet conduit 121 includes a central axis 804 which ispreferably at an acute angle of θ with respect to the cylinder wall 35.The angle θ is preferably approximately 45°, although it is envisionedthat other angles θ may be used.

In FIG. 68, a further embodiment of an inlet opening of a conduit 121 isshown. In this embodiment, a low pressure region is encouraged so thatlubricant within the exhaust gas condenses into a large generallycylindrical chamber 810. The gases enter through a small orifice 812opening to the cylinder 35. The opening diverges at a surface 814 intothe chamber 810, which is preferably formed within the engine block 34.The opening converges at a surface 815 to which the inlet conduit 121 isconnected. As shown by the arrow 816, a portion of the gas flow isdirected upward into the chamber 810 creating a low-pressure region tofacilitate condensation of lubricant therein. Optionally, a drain hole(not shown) may be provided at a lower portion of the chamber 810 todrain condensed lubricant.

FIGS. 69a and 69b illustrate a cylinder in two views wherein the inletconduit 121 leading to the oxygen sensor of the present invention opensinto the combustion chamber 59 via a flanged opening 122 provided in thecylinder head 61. A similar arrangement was shown previously withrespect to FIG. 62.

Although the various inlet openings of conduits 121 are shown openinginto various cylinders, these inlets may also open into other portionsof the exhaust system of the engine as described previously. Moreparticularly, the sensor assembly 91 may sample combustion gases fromvarious locations in the exhaust system, such as from the exhaustpassage 71 as shown in FIGS. 23 and 24, or from the exhaust manifold 68as shown in FIG. 25. In all of these cases, the preferred shape of theinlet opening 121 either smoothes the exhaust gas flow therethrough toreduce lubricant condensation, or provides a condensation chamber withinwhich the lubricant can condense before it reaches the oxygen sensorelement 109.

From the foregoing description, it should be readily apparent that thedescribed embodiments of the invention not only provide a very effectiveexhaust sensor arrangement that can be utilized with two-cycle engines,but also ensures that the sensor will have a long life and be relativelyfree of contamination and deterioration in output. Of course, thoseskilled in the art will recognize that various changes and modificationsmay be made without departing from the spirit and scope of theinvention, as defined by the appended claims.

I claim:
 1. A control system for a 2-cycle, crankcase compression,internal combustion engine having a combustion chamber that varies involume cyclically during engine operation, an exhaust system forreceiving exhaust gases from said combustion chamber during a cycle ofengine operation, a fuel supply system for supplying fuel to said enginefor combustion in said combustion chamber, an accumulator chamber forproviding a volume in which exhaust gases from said combustion chambermay accumulate and communicating with said combustion chamber for atleast a portion of the engine operating cycle, a sensor in saidaccumulator chamber for providing a control signal for control of saidfuel supply system, and protecting means for preventing oil and saidexhaust gases from contaminating said sensor comprising coating theinner surface of said accumulator chamber with a catalytic material. 2.A control system as set forth in claim 1 wherein said protecting meanscomprises coating substantially all of the inner surface of saidaccumulator chamber with a catalytic material.
 3. A control system asset forth in claim 1 wherein said catalytic material acceleratesoxidation of said oil and exhaust gases entering said accumulatorchamber.
 4. A control system as set forth in claim 1, wherein saidcatalytic material comprises platinum.
 5. A control system as set forthin claim 1, wherein said accumulator chamber is formed from an outerhousing defining a cavity therein into which said sensor protrudes andwhich outer housing communicates with said combustion chamber.
 6. Acontrol system as set forth in claim 5, wherein said sensor threadinglyengages said outer housing.
 7. A control system as set forth in claim 5,wherein said accumulator chamber outer housing and said sensor aremounted within a protective recess formed in said engine so as toprevent possible impact injury to said sensor.
 8. A control system asset forth in claim 5, wherein said accumulator chamber outer housing andsaid sensor are mounted on the cylinder head of said engine.
 9. Acontrol system as set forth in claim 5, wherein a protective cover isprovided over said accumulator chamber outer housing and said sensor soas to protect said sensor from possible impact injury.
 10. A controlsystem as set forth in claim 1, wherein said sensor displaces less thanone-half of the volume of said accumulator chamber.
 11. A control systemas set forth in claim 10, wherein the communication of said accumulatorchamber with said combustion chamber permits bidirectional flow ofexhaust gases into and out of said accumulator chamber.
 12. A controlsystem as set forth in claim 1, wherein the flow of exhaust gases fromthe combustion chamber into said accumulator chamber occurs only at theend of the combustion phase of said engine.
 13. A control system as setforth in claim 12, wherein said engine is a ported engine having anexhaust port and said combustion chamber communicates with saidaccumulator chamber at a time substantially equal to the time when theexhaust port initially opens.
 14. A control system as set forth in claim1 comprising a discharge conduit for discharging gases from saidaccumulator chamber to another portion of said engine so that the flowof exhaust gases through said accumulator chamber will be substantiallyunidirectional.
 15. A control system as set forth in claim 14, whereinsaid discharge conduit discharges into a second combustion chamber ofsaid engine.
 16. A control system as set forth in claim 14, wherein saiddischarge conduit discharges into said exhaust system of said engine.17. A control system as set forth in claim 14, wherein said dischargeconduit discharges into an induction system of said engine.
 18. Acontrol system as set forth in claim 14, wherein said engine is acrankcase compression 2-cycle engine and said discharge conduitdischarges into a crankcase chamber of said engine.
 19. A control systemas set forth in claim 1, wherein the communication of the accumulatorchamber with the combustion chamber is through a cylinder head of saidengine.
 20. A control system as set forth in claim 1, wherein thecommunication of the accumulator chamber with said combustion chamber isthrough a passageway formed in said cylinder head.
 21. A control systemas set forth in claim 1, wherein the communication of the accumulatorchamber with the combustion chamber is through an exhaust system of saidengine.
 22. A control system as set forth in claim 1, further comprisinga filter disposed in the flow path of exhaust gases provided to saidaccumulator chamber.
 23. A control system as set forth in claim 22,wherein said filter comprises a replaceable filter element.
 24. Acontrol system as set forth in claim 23, wherein said replaceable filterelement is cylindrical.
 25. A control system as set forth in claim 1,further comprising means for directing saturated exhaust vapors awayfrom said sensor disposed in said accumulator chamber.
 26. A controlsystem as set forth in claim 25, comprising an inlet conduit fordelivering exhaust gases to said accumulator chamber, and wherein saidinlet conduit is spaced substantially away from said sensor.
 27. Acontrol system as set forth in claim 26, further comprising an outletconduit connected to said accumulator chamber for discharging exhaustgases therefrom, and wherein said outlet conduit is spaced further fromsaid sensor than said inlet conduit such that the exhaust gases mustflow from the inlet conduit away from said sensor to said outletconduit.
 28. A control system as set forth in claim 25, comprising aninlet conduit for delivering exhaust gases to said accumulator chamberand an outlet conduit for discharging exhaust gases from saidaccumulator chamber, and wherein at least one of said inlet or outletconduits extends into said accumulator chamber and is spacedsubstantially away from said inner surface of said accumulator chamber.29. A control system as set forth in claim 28, wherein both said inletand outlet conduits extend into said accumulator chamber and are spacedsubstantially away from said inner surface of said accumulator chamber.30. A control system as set forth in claim 1, further comprising aprotective sleeve placed around said sensor.
 31. A control system as setforth in claim 30, wherein said sleeve has perforations formed on thesides of said sleeve disposed away from the flow of exhaust gasesentering said accumulation chamber and substantially no perforationsformed on the side of said sleeve in the flow path of exhaust gasesentering said accumulator chamber.
 32. A control system as set forth inclaim 1, further comprising a restrictive orifice disposed in the flowpath of exhaust gases entering said accumulator chamber.
 33. A controlsystem as set forth in claim 32, wherein said orifice forms a convergentdivergent nozzle through which said exhaust gases must pass beforeentering said accumulator chamber.
 34. A control system as set forth inclaim 1, further including means for draining condensed liquids fromsaid accumulator chamber.
 35. A control system as set forth in claim 34,wherein said draining means comprises a restricted drain orifice.
 36. Acontrol system as set forth in claim 35, wherein said drain orifice isformed with a conical surface surrounding its outlet side forrestricting the backflow of gases into to said accumulator chamberthrough said drain orifice.
 37. A control system as set forth in claim1, further comprising means for maintaining a high temperature aroundthe sensor so as to reduce the likelihood of said exhaust vaporsbecoming saturated and condensing on said sensor.
 38. A control systemas set forth in claim 37, wherein said temperature maintaining meanscomprises an insulating material placed around said accumulator chamber.39. A control system as set forth in claim 38, wherein said insulatingmaterial is provided between said sensor and the housing that forms saidaccumulator chamber.
 40. A control system as set forth in claim 37,wherein said temperature maintaining means comprises a heater disposedin said accumulator chamber and surrounding said sensor.
 41. A controlsystem as set forth in claim 1, further comprising means for cooling aportion of the inner surface of said accumulating chamber so as to causeany condensation of oil to occur away from said sensor.
 42. A controlsystem as set forth in claim 41, wherein said cooling means comprises acooling channel formed around said accumulation chamber through whichengine coolant is circulated.
 43. A control system as set forth in claim41, further including a drain area below said accumulator chamberwherein condensed liquids may be accumulated and drained.
 44. A controlsystem as set forth in claim 1, further comprising a second accumulationchamber in communication with said first accumulation chamber in whichsaid sensor is provided, whereby said exhaust gases must flow throughboth accumulator chambers before contacting said sensor.
 45. A controlsystem as set forth in claim 44, wherein the inner surface of saidsecond accumulation chamber is coated with a catalytic material.
 46. Acontrol system as set forth in claim 44, further including a drain areabelow said second accumulator chamber wherein condensed liquids may beaccumulated and drained.
 47. A control system as set forth in claim 44,wherein communication between the said first and second accumulatorchambers is provided by a restricted orifice.
 48. A control system asset forth in claim 47, wherein the exhaust gases are first delivered tosaid second accumulator chamber through a perforated inlet tube.
 49. Acontrol system for a 2-cycle, crankcase compression, internal combustionengine having a combustion chamber that varies in volume cyclicallyduring engine operation, an exhaust system for receiving exhaust gasesfrom said combustion chamber during a cycle of engine operation, a fuelsupply system for supplying fuel to said engine for combustion in saidcombustion chamber, an accumulator chamber for providing a volume inwhich exhaust gases from said combustion chamber may accumulate andcommunicating with said combustion chamber for at least a portion of theengine operating cycle, a sensor in said accumulator chamber forproviding a control signal for control of said fuel supply system, andprotecting means for preventing oil and said exhaust gases fromcontaminating said sensor comprising a replaceable filter elementdisposed in the flow path of exhaust gases flowing into said accumulatorchamber.
 50. A control system as set forth in claim 49, wherein saidfilter element is cylindrical.
 51. A control system as set forth inclaim 50, wherein said filter comprises a filter body having a cavitydisposed therein for receiving said filter element, an inlet end and anoutlet end disposed on either side of said filter element and a capsealingly engaging said filter body.
 52. A control system as set forthin claim 51, wherein said cap threadingly engages said filter body so asto facilitate removal and replacement of said filter element.
 53. Acontrol system as set forth in claim 51, wherein said cap comprises athreaded outer retainer element adapted to threadingly engage saidfilter body and an inner sealing element adapted to sealingly engagesaid filter body.
 54. A control system as set forth in claim 53, furthercomprising a spring disposed in said filter body between said filterelement and said cap to maintain said filter element in operativeengagement with said filter body.
 55. A control system as set forth inclaim 49, wherein said spring is adapted to allow said filter element tomove out of the path of exhaust gases flowing into said accumulatorchamber when said filter element is clogged.
 56. A control system as setforth in claim 49, wherein the inner surface of said accumulator chamberis coated with a catalytic material.
 57. A control system as set forthin claim 56, wherein said catalytic material comprises platinum.
 58. Acontrol system as set forth in claim 49, wherein said accumulatorchamber is formed by an outer housing defining a cavity therein intowhich said sensor protrudes and which outer housing communicates withsaid combustion chamber.
 59. A control system as set forth in claim 58,wherein said sensor threadingly engages said outer housing.
 60. Acontrol system as set forth in claim 58, wherein said accumulatorchamber outer housing and said sensor are mounted within a protectiverecess formed in said engine so as to prevent possible impact injury tosaid sensor.
 61. A control system as set forth in claim 58, wherein saidaccumulator chamber outer housing and said sensor are mounted on thecylinder head of said engine.
 62. A control system as set forth in claim58, wherein a protective cover is provided over said accumulator chamberouter housing and said sensor so as to protect said sensor from possibleimpact injury.
 63. A control system as set forth in claim 49, whereinsaid sensor displaces less than one-half of the volume of saidaccumulator chamber.
 64. A control system as set forth in claim 63,wherein the communication of said accumulator chamber with saidcombustion chamber permits bidirectional flow of exhaust gases into andout of said accumulator chamber.
 65. A control system as set forth inclaim 49, wherein the flow of exhaust gases from the combustion chamberinto said accumulator chamber occurs only at the end of the combustionphase of said engine.
 66. A control system as set forth in claim 49comprising a discharge conduit for discharging gases from saidaccumulator chamber to another portion of said engine so that the flowof exhaust gases through said accumulator chamber will be substantiallyunidirectional.
 67. A control system as set forth in claim 68, whereinsaid discharge conduit discharges into a second combustion chamber ofsaid engine.
 68. A control system as set forth in claim 49, wherein thecommunication of the accumulator chamber with said combustion chamber isthrough a passageway formed in the cylinder head of said engine.
 69. Acontrol system as set forth in claim 49, further comprising means fordirecting saturated exhaust vapors away from said sensor disposed insaid accumulator chamber.
 70. A control system as set forth in claim 49,further comprising a protective sleeve placed around said sensor, saidsleeve having perforations formed on the sides of said sleeve disposedaway from the flow of exhaust gases entering said accumulation chamberand having substantially no perforations formed on the sides of saidsleeve disposed in the flow path of exhaust gases entering saidaccumulator chamber.
 71. A control system as set forth in claim 49,further comprising means for maintaining a high temperature around thesensor so as to reduce the likelihood of said exhaust vapors becomingsaturated and condensing on said sensor.
 72. A control system as setforth in claim 49, further comprising means for cooling the innersurface of said accumulating chamber so as to cause any condensation ofoil to occur away from said sensor.
 73. A control system for a 2-cycle,crankcase compression, internal combustion engine having a combustionchamber that varies in volume cyclically during engine operation, anexhaust system for receiving exhaust gases from said combustion chamberduring a cycle of engine operation, a fuel supply system for supplyingfuel to said engine for combustion in said combustion chamber, anaccumulator chamber for providing a volume in which exhaust gases fromsaid combustion chamber may accumulate and communicating with saidcombustion chamber for at least a portion of the engine operating cycle,a sensor in said accumulator chamber for providing a control signal forcontrol of said fuel supply system, and protecting means for preventingoil and said exhaust gases from contaminating said sensor comprising aprotective sleeve comprised of a cylindrical sleeve configured to fitover said sensor and having perforations on the sides of said sleevedisposed away from the flow path of exhaust gases entering saidaccumulation chamber and substantially no perforations formed on thesides of said sleeve disposed in the flow path of exhaust gases enteringsaid accumulator chamber.
 74. A control system as set forth in claim 73,further comprising means for directing saturated exhaust vapors awayfrom said sensor disposed in said protective sleeve in said accumulatorchamber.
 75. A control system as set forth in claim 73, wherein saidaccumulator chamber receives exhaust gases from an inlet conduit anddischarges exhaust gases through an outlet conduit connected and whereinsaid outlet conduit is spaced further from said sensor than said inletconduit such that the exhaust gases must flow from the inlet conduitaway from said sensor to said outlet conduit.
 76. A control system asset forth in claim 73, wherein said accumulator chamber is formed by anouter housing defining a cavity therein into which at least a portion ofsaid sensor protrudes and which outer housing communicates with saidcombustion chamber.
 77. A control system as set forth in claim 76,wherein said sensor threadingly engages said outer housing and whereinsaid protective sleeve surrounds the portion of said sensor protrudinginto said accumulator chamber for protecting said sensor fromcontamination.
 78. A control system as set forth in claim 76, whereinsaid accumulator chamber outer housing and said sensor are mountedwithin a protective recess formed in said engine so as to preventpossible impact injury to said sensor.
 79. A control system as set forthin claim 76, wherein said accumulator chamber outer housing and saidsensor are mounted on the cylinder head of said engine.
 80. A controlsystem as set forth in claim 76, wherein a protective cover is providedover said accumulator chamber outer housing and said sensor so as toprotect said sensor from possible impact injury.
 81. A control system asset forth in claim 73, wherein the inner surface of said accumulatorchamber is coated with a catalytic material.
 82. A control system as setforth in claim 81, wherein said catalytic material comprises platinum.83. A control system as set forth in claim 73, wherein the communicationof said accumulator chamber with said combustion chamber permitsbidirectional flow of exhaust gases into and out of said accumulatorchamber.
 84. A control system as set forth in claim 73, wherein the flowof exhaust gases from the combustion chamber into said accumulatorchamber occurs only at the end of the combustion phase of said engine.85. A control system as set forth in claim 73 comprising a dischargeconduit for discharging gases from said accumulator chamber to anotherportion of said engine so that the flow of exhaust gases through saidaccumulator chamber will be substantially unidirectional.
 86. A controlsystem as set forth in claim 85, wherein said discharge conduitdischarges into a second combustion chamber of said engine.
 87. Acontrol system as set forth in claim 73, further comprising a filterdisposed in the flow path of exhaust gases provided to said accumulatorchamber for preventing oil in the exhaust gases from contaminating saidsensor.
 88. A control system as set forth in claim 87, wherein saidfilter comprises a replaceable filter element.
 89. A control system asset forth in claim 73, further comprising an orifice disposed in theflow path of exhaust gases entering said accumulator chamber forming aconvergent-divergent nozzle through which said exhaust gases must passbefore entering said accumulator chamber.
 90. A control system as setforth in claim 73, further comprising means for draining condensedliquids from said accumulator chamber.
 91. A control system as set forthin claim 90, wherein said draining means comprises a restricted drainorifice.
 92. A control system as set forth in claim 91, wherein saiddrain orifice is formed with a conical surface surrounding its outletside for restricting the backflow of gases into to said accumulatorchamber through said drain orifice.
 93. A control system as set forth inclaim 73, further comprising means for maintaining a high temperaturearound said sensor so as to reduce the likelihood of said exhaust vaporsbecoming saturated and condensing on said sensor.
 94. A control systemas set forth in claim 73, further comprising means for cooling the innersurface of said accumulating chamber so as to cause any condensation ofoil to occur away from said sensor.